Spectroscopic and magnetochemical studies on several multisite oxidases are proposed. The principal objectives are (1) to elucidate the structure of the type 1 copper site in fungal laccase by use of resonance Raman spectroscopy, (2) to study intersite interactions through examination of the magnetic behavior of the metal sites in cytochrome aa3, cytochrome cd, human ceruloplasmin, and a type 2 copper-depleted derivative of Rhus laccase, (3) to further examine the catalytic significance of steady-state oxygen-intermediates in the laccase reaction, and extend these studies to ceruloplasmin and the type 2 copper-depleted derivative of laccase, and (4) to study the role of the type 2 copper of laccase incorporating other metals into the vacant type 2 site in the type 2-depleted laccase.